As magnetic tape cartridges so far used as recording media for external memory unit of, e.g., computers, a magnetic tape cartridge of the type comprising a cartridge case rotatably housing one or a plurality of reels on which a magnetic tape is wound is known. Since these magnetic tapes are used for the storage of computer data and important data are stored, these magnetic tape cartridges are constituted so that a trouble such as tape jamming does not occur and magnetic tapes are not taken out carelessly.
In a single reel type cartridge, a magnetic tape drive is constituted such that leader components such as a leader pin and a leader block for loading a magnetic tape are fixed at the tip of the magnetic tape, or a leader tape of a relatively hard plastic material having a hole for hitching punched at the tip thereof is joined onto the tip of the magnetic tape, and loading/unloading of the magnetic tape are done by holding and loading the leader components or the tip of the leader tape by the holding component of a recording/reproducing apparatus.
When loading/unloading of a magnetic tape are done by drawing the tip of the magnetic tape to the side of a magnetic recording/reproducing apparatus and winding the tip of the tape on a drive reel in the apparatus, it is preferred to reinforce the tape, since the tape is susceptible to damage if the tip of the tape is brought into contact with a tape guide and a magnetic head arranged in the traveling route in the state of not correctly being positioned and pulled.
It is also preferred to do reinforcement for the purpose of preventing the difference in levels of leader block generated on a drive reel from imprinting on a data-recording magnetic tape to thereby increase dropout, and splicing of a leader tape stronger than a magnetic tape on the tip of the magnetic tape is performed to cope with this phenomenon (refer to JP-A-2001-110164 (The term “JP-A” as used herein refers to an “unexamined published Japanese patent application”.)).
When a magnetic tape cartridge is mounted on an LTO drive and load/unload are repeated, the surface of the leader tape that is rubbed with the running system of the LTO drive is scratched and the shavings adhere to the running system. The adhered shavings are transferred to the magnetic tape surface to cause the problem of the increase of dropout. In addition, the leader tape is deformed and the deformation is imprinted on the magnetic tape, which causes the deterioration of error rate.
The leader block is to be installed in the concavity of the core of a winding reel and a part of the leader block forms a part of the arc of the core in that state.
Explaining the structure typically, as shown in FIG. 4A, leader block 40 is invaginated in concavity 42 provided along the diameter direction of core 41, and end face 40a of leader block 40 constitutes a part of winding surface of core 41 in this state. End face 40a of leader block 40 forms arc for smoothly winding a magnetic tape MT corresponding to the peripheral surface of core 41 as shown in FIG. 4A.
However, in these conventional tape drives, depending upon the dimensional accuracy of leader block 40 constituting a part of the winding surface, as shown in FIG. 4B, end face 40a protrudes from core 41 and an unallowable difference in levels is formed on the winding surface of core 41 in some cases.
Such a difference in levels causes a crease and deformation on leader tape LT and, as shown in FIG. 4C, these crease (fold) and deformation are also formed on the same parts of magnetic tape MT, which are substantially recording areas, wound in the next layer on (so-called tape imprinting is generated). The tape imprinting is liable to cause such disadvantages that the proper distance between the tape and the recording/reproducing heads cannot be maintained during the process of recording and reproducing of data, which results in recording impossibility and the loss of data.
If a period of time when magnetic tape MT is wound on a winding reel is short, generation of the problem of imprinting is less, but when magnetic tape MT is used after being allowed to stand in the state of being wound on a reel, regular tape imprinting is sometimes formed on the surface of magnetic tape MT in almost equal pitch to the circumferential length of core 41.